1. Field of the Invention
The present invention relates to a method of controlling a transmission of a router and, more particularly, to a method of controlling the transmission of the router using polling.
2. Background of the Related Art
Generally, a router is an apparatus connecting networks having different lower hierarchy structures. The router transmits packet data (hereinafter abbreviated packet) through an optimal path established in connection with a routing table, as well as connects the received packet to another network or a target node of its own network.
There are two methods for controlling a transmission of a router, these are the interrupt-based method and the polling method. When a packet is received using the interrupt-based method, the corresponding port produces an interrupt signal so as to inform a controller of the packet's arrival. In the polling method, the controller polls the respective ports periodically or successively to make the corresponding port process the received packet.
FIG. 1 illustrates a block diagram of the inner structure of a router used in connection with the polling method. Router 100 connects the corresponding destination or a by-way-of the destination so that packets received through the respective ports 20, 30, 40, and 50 are transferred via the most suitable path. The traffic supported by each of the ports 20, 30, 40, and 50 depends on a line speed and circuit capacity of the connected network.
Controller 10 sends a poll to the respective ports 20, 30, 40, and 50 periodically or successively. The port receiving the poll transmits a received packet to the controller 10. Then, the controller routes the packet to its destination through an optimal path.
Ports 20, 30, 40, and 50 are unable to process the received packet until receiving the poll. When the poll is received from the controller 10, the received packet is transmitted to the controller 10. If an amount of the received packet overflows the capacity of the port, so as not to complete the transmission, the packet continues being received until the next poll is received.
In such a polling method, the controller 10 polls all of the ports successively and fairly, but fails to consider the traffic supported by the respective ports or the transmission speed of the packet. Polling is carried out on ports having high and low traffic volumes without distinction, thereby reducing the system efficiency. Also, the polling method fails to respond to burst traffic properly, thereby reducing the performance of the router. Moreover, the packet may be destroyed if an overflow occurs, due to the abrupt increase of a traffic through a specific port.